Toyota Repair: bearing noise?, sr5 v6, drive belts

Question
my 1994 sr5 v6 toyota truck has developed a motor noise i first thought might be the water pump going out. i now believe it could be the ac pump. it sounds like a bearing or valve rattle. the engine has almost 150k on it and has been well maintained. does this sound like something you've seen before. i think the sound is coming from the belts on the power steering side. no over heating has occured. it has the 5 speed manual transmission 4wd.

Answer
To eliminate the a/c compressor as the cause for the noise you could remove all the drive belts and run the engine, if the noise is still there then it would indicate that it is an internal engine noise, the water pump is a good possibility. A worn timing belt can also cause the noise.